For decades, we’ve heard that access to clean water changes everything. Not only does it improve the health of entire communities, it also gives women freedom to earn an income and children time to go to school, when they don’t have to spend hours walking miles every day just to gather water. That’s why global progress has been rightly celebrated: Between 2000 and 2015, 1.6 billion people gained access to clean water for the first time.

But according to the UN Children’s Fund (UNICEF), as much as 30 to 50 percent of water, sanitation and hygiene (WASH) projects fail after just two to five years, leaving recipients of the new wells, toilets or other projects back where they started – even worse off sometimes. This has led to calls for the WASH sector to be more upfront about failures and understanding what went wrong. Without learning from mistakes, we will miss the mark on Sustainable Development Goal 6: to ensure the availability and sustainable management of water and sanitation for all.

There are many reasons why water projects fail. But Kirk Anderson, director of international programs at Water1st, says the failure rate is not unique to the WASH sector. In fact, he says that most development efforts suffer problems with sustainability, simply because of the nature of aid.

In a market system, when buyers do not purchase faulty, poor or unwanted products, manufacturers quickly get the message that they need to either improve their product or go out of business. But in a donor system, the users are not the buyers. Therefore, unless the buyers (development organizations, in this case) are regularly asking the users for feedback – and the users are willing to give honest feedback about the gift they received – buyers often continue to fund and implement faulty, poor or unwanted programs.

Read the full story about how to build water systems that last by Joanna Lu at Global Washington.